Engineering Mechanics - Force System Resultants

Exercise :: Force System Resultants - General QuestionsForce System Resultants - General Questions
11.

Determine the moment of force F_{3} about point A on the beam.

A.
M3 = 6930 ft-lb _{} B.
M3 = 6000 ft-lb _{} C.
M3 = 3000 ft-lb _{} D.
M3 = 4000 ft-lb _{}

Answer: Option C

Explanation:

12.

Replace the force at A by an equivalent force and couple moment at P . Express the results on Cartesian vector form.

A.
F = (-50i +20j +30k) N, M = (50i -130j +170k) N-m B.
F = (-50i +20j +30k) N, M = (-50i +60j +60k) N-m C.
F = (50i -20j -30k) N, M = (-50i +130j -170k) N-m D.
F = (50i -20j -30k) N, M = (50i -60j -60k) N-m

Answer: Option C

Explanation:

13.

Replace the force at A by an equivalent force and couple moment at P . Express the results on Cartesian vector form.

A.
F = (60j -80k ) lb, M = (20i +160j +120k ) lb-ftB.
F = (60j -80k ) lb, M = (300j +560k ) lb-ftC.
F = (60j -80k ) lb, M = 20i lb-ftD.
F = (60j -80k ) lb, M = (-160i -400j +120k ) lb-ft

Answer: Option A

Explanation:

14.

A force and couple act on the pipe assembly. Replace this system by an equivalent single resultant force. Specify the location of the resultant force along the y axis, measured from A . The pipe lies in the x -y plane.

A.
R = 25k lb, y = -0.9 ft B.
R = 25k lb, y = 0.9 ft C.
R = 25k lb, y = 3.9 ft D.
R = 25k lb, y = -3.9 ft

Answer: Option A

Explanation:

15.

Determine the couple moment. Use a vector analysis and express the result as a Cartesian vector.

A.
M = (800i -4800j -800k ) lb-ftB.
M = (4000i -2000j +4000k ) lb-ftC.
M = (-4000i +7000j -4000k ) lb-ftD.
M = (-800i -4800j -800k ) lb-ft

Answer: Option B

Explanation: